Mixtures of cell types can be analyzed by having at least two signal markers, with at least one at three different levels to provide a barcode for each cell type. The mixture of cells may be subjected to a common candidate moiety and the effect of the moiety on the cells determined along with identification of the cell by the barcode. Conveniently, surface marker proteins and labeled antibodies can be used to create the barcode and the cells analyzed with flow cytometry.